Electrode slurry, electrode and process for producing the same, and secondary battery

Patent metadata

Field	Value
Publication number	US-11094934-B2
Application number	US-201816474594-A
Country	US
Kind code	B2
Filing date	Jan 10, 2018
Priority date	Jan 17, 2017
Publication date	Aug 17, 2021
Grant date	Aug 17, 2021

Abstract

An electrode slurry contains (A) a cellulose fiber and (C) an electrode active material, the electrode active material (C) contains at least a silicon particle and may contain a silicon particle and a carbonaceous particle. The slurry may further contain (B) a carboxymethyl-group-containing cellulose ether or a salt thereof. The average fiber length L (1 to 750 μm) of the cellulose fiber (A) is larger than the average particle size D Si (1 nm to 1 μm) of the silicon particle as the electrode active material (C). The average particle size ratio L/D Si is 5 to 15,000. The electrode slurry can improve a discharge capacity and is useful for forming an electrode of a non-aqueous secondary battery (lithium-ion secondary battery) that can maintain a high discharge capacity after repeated charging and discharging.

First claim

The invention claimed is:

1. An electrode slurry comprising:
(A) a cellulose fiber and (C) an electrode active material consisting essentially of a carbonaceous particle and a silicon particle in a ratio of the former/the latter of 99/1 to 50/50 (weight ratio),
the cellulose fiber (A) having an average fiber length of 1 to 750 μm,
the silicon particle as the electrode active material (C) having an average particle size of 1 nm to 1 μm, and
the average fiber length of the cellulose fiber (A) being larger than the average particle size of the silicon particle as the electrode active material (C),
wherein a ratio L/D Si is 20 to 15,000, where L represents the average fiber length of the cellulose fiber (A), and D Si represents the average particle size of the silicon particle as the electrode active material (C).

2. The electrode slurry according to claim 1 , wherein the cellulose fiber (A) contains a cellulose nanofiber having a nanometer-sized average fiber diameter.

3. The electrode slurry according to claim 1 , wherein the average particle size of the silicon particle is smaller than an average particle size of the carbonaceous particle.

4. The electrode slurry according to claim 1 , wherein
a ratio D c /D Si is 5 to 1,000, where D c represents an average particle size of the carbonaceous particle, and D Si represents the average particle size of the silicon particle, and
a ratio L/D c is not less than 0.1, where L represents the average fiber length of the cellulose fiber (A), and D c represents the average particle size of the carbonaceous particle as the electrode active material (C).

5. The electrode slurry according to claim 1 , which further contains (B) a carboxymethyl-group-containing cellulose ether or a salt thereof.

6. The electrode slurry according to claim 1 , which further contains (B) a carboxymethyl-group-containing cellulose ether or a salt thereof, wherein
the cellulose fiber (A) contains a cellulose nanofiber having an average fiber length of 2 to 100 μm,
the carboxymethyl-group-containing cellulose or the salt thereof (B) contains a carboxymethyl cellulose or a salt thereof, and
a ratio of the cellulose fiber (A) relative to the carboxymethyl-group-containing cellulose ether or the salt thereof (B) is 95/5 to 20/80 in the former/the latter (weight ratio) in terms of solid content.

7. The electrode slurry according to claim 1 , which further contains (B) a carboxymethyl-group-containing cellulose ether or a salt thereof, wherein, in terms of solid content, a total content of the cellulose fiber (A) and the carboxymethyl-group-containing cellulose ether or the salt thereof (B) is 1 to 5 parts by weight based on 100 parts by weight of a total amount of the cellulose fiber (A), the carboxymethyl-group-containing cellulose ether or the salt thereof (B), and the electrode active material (C).

8. The electrode slurry according to claim 5 , wherein, in terms of solid content, an amount of the carboxymethyl-group-containing cellulose ether or the salt thereof (B) is 0.1 to 3 parts by weight based on 100 parts by weight of a total amount of the cellulose fiber (A), the carboxymethyl-group-containing cellulose ether or the salt thereof (B), and the electrode active material (C).

9. The electrode slurry according to claim 1 , which further contains a carboxymethyl cellulose or a salt thereof (B), wherein
the cellulose fiber (A) comprises a cellulose nanofiber having a nanometer-sized average fiber diameter,
the electrode active material (C) consists essentially of the carbonaceous particle and the silicon particle in a ratio of the former/the latter of 98/2 to 70/30 (weight ratio), and
in terms of solid content, an amount of the component (A) is 0.1 to 3 parts by weight and a total amount of the component (A) and the component (B) is 1 to 4 parts by weight based on 100 parts by weight of a total amount of the component (A), the component (B), and the component (C).

10. A non-aqueous secondary battery electrode comprising a current collector and an electrode active material layer on at least one surface of the current collector, the electrode active material layer containing an electrode active material, wherein the electrode active material layer contains (A) a cellulose fiber and (C) an electrode active material recited in claim 1 .

11. The electrode according to claim 10 , which is a positive electrode or a negative electrode of a lithium-ion secondary battery.

12. A non-aqueous secondary battery provided with an electrode recited in claim 10 .

13. The electrode slurry according to claim 1 , which further contains (B) a carboxymethyl-group-containing cellulose ether or a salt thereof, wherein
the cellulose fiber (A) contains a cellulose nanofiber having an average fiber length of 2 to 100 μm,
the carboxymethyl-group-containing cellulose or the salt thereof (B) contains a carboxymethyl cellulose or a salt thereof, and
a ratio of the cellulose fiber (A) relative to the carboxymethyl-group-containing cellulose ether or the salt thereof (B) is 85/15 to 20/80 in the former/the latter (weight ratio) in terms of solid content.

14. A non-aqueous secondary battery electrode comprising a current collector and an electrode active material layer on at least one surface of the current collector, the electrode active material layer containing an electrode active material, wherein the electrode active material layer contains (A) a cellulose fiber, (B) a carboxymethyl-group-containing cellulose ether or a salt thereof, and (C) an electrode active material recited in claim 5 .

15. The electrode according to claim 14 , which is a positive electrode or a negative electrode of a lithium-ion secondary battery.

16. A non-aqueous secondary battery provided with an electrode recited in claim 14 .

Assignees

• Daicel Corp
• Daicel Finechem Ltd

Inventors

• Iwaya Masao
• Ono Shinya
• Doi Naoki

Classifications

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M4/622

  being polymers · CPC title

• H01M4/386 Primary

  Silicon or alloys based on silicon · CPC title

• H01M4/364

  as mixtures · CPC title

• H01M4/0404

  by coating on electrode collectors · CPC title